Photograph and method of making the same



June 26,'1923. l

' A. A|V|ES, JR

PHOTOGRAPH AND METHOD AoF MAKING THE SAME Filed Jamv 12, 1920 mvenor. WAHM/Q12 .@QALM n4, ad@

' zo 24 @323640+44652 064m Patentcd .lune 26, 1923.

sra'rns PHOTOGRAPH AND METHOD OF MAKING THE SAME.

Application led January `12, 1920.' Serial No. 351,012.

To all lwhom t concern:

Be it known that I, ADELBERT AMES, Jr., a citizen of the United States, and resident of Tewksbury, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Photographs and Methodsy of Making the Same, of which the following is a specification.

This invention relates to photography, and is particularly concerned with both the character of the photographic picture and the means employed for obtaining such a picture.

Photography as heretofore carried out 1n a pictorial sense has aimed to present to perception a record of the natural things portrayed recognizable, with more or less aid by the imagination, as a reproduction of '20 the objects depicted. Y

At best, photographs are limited to a partial presentation only of the factors or qual- .it-ies giving distinouishing appearance to natural objectsas viewed by the human eye.

25, The natural objects are tri-dimensional, but

the photograph must be viewed as a plane projection, either as thrown upon a screen, as a transparency seen against an illuminated background, or as an arrangement of light and dark places on a paper or other surface. The complete illusion of looking at the object pictured is not reached by any photograph because of the artificiality of the picture due to these reasons. Absence of color is of course also a factor in failure of illusion, but not the most important factor.

Apart from these inherent qualities of any photograph, photography as heretofore practiced has also falled of illusion 1n more subtle qualities. The makers of lenses have sought mathematically exact definition, absence of distortion and correction of diffusion at all parts of the field represented by the photographic picture, so that the average photograph contains a too faithul record of the detailed outline and light and shadow in every portion of the angular field of View represented by the print or screen image constituting the picture.

Persons skilled in the graphic arts and Vcompetent critics of artistic effort have long matic translation of the appearance of polychromatic values, and lack of i proper range of value from light to complete shadow.

In my application of even date herewith Serial No. 351,011, filed January 12, 1920, I have explained a new type of photograph, and a new lens system for practicing a method of forming images having the characteristic diffusions, aberrations and distor-l tions of the subjective impression of the object-field as perceived by the eye.

I have further devised an art of and apparatus for making, and a photograph characterized by a distribution of sensitiveness to color, ,a,dapted for use with the method and apparatus of my said application o-r with ordinary photographic methods and appliances, and when so used further contributing to the appearance of the photograph characteristics adapted to be recognized as characteristics of the subjective impression of thev appearance of natural objects vmade upon the normal I at an angle to this line of sight, in the object eye.

The present invention has to do with the simulation ofthe sensitiveness of the retinal surface of the eye, especially in respect to stimulation by color. Discovery by re-y search shows amarked selective distribution of sensitivity to color of the human eye, and. I shall hereindescribe contributions to the art for the purpose of causing photographic pictures to conform, whether monochromatic or polychromatic, to the appearance expected by the normal eye in respect to the value of representations of differently colored. objects, yespecially in respect to the position of the object in the line of sight or center of interest, or elsewhere field.

One aspect of my invention is particularly applicable to the making of monochromatic component pictures for selective color by superposition of differently colored vmonochromes, thus making polychromatic photographs in the colors of nature. One subordinate object of the invention is to provide means for securing avariable sensitivenes's of the'pplate with respect to a colored -impression While maintaining uniformity or other predetermined distribution of degree of sensitiveness in a quantitative sense upon the plate in relation to its axial centerr'and. angular regions. v

In the accompanying drawings,-

Figure 1 is a diagram in plan illustrating central areas of the completed photograph and of selective screens employed between the plate and the photographic lens; g

Figure 2 is a section on the line 2 2 of. Fig. 1, illustrating a typical arrangement according to the invention; andI Figure?) is a diagram illustrating quantitatively the distribution of intensities of perception of light of different wave lengths or colors in respect to the retina of the normal eye, and also showing the distribution of intensities of perception at low illuminations.

Referring to the drawings, photographs corresponding to the invention are positive or negative projections, transparencies or prints produced by any preferred process from a negative A, Fig. 2, which may comprise any preferred sensitive emulsion coat` l ing a on yany kind of backing b such as the fiat glass plate indicated, when suitably exposed and devel@ ed.

For the particu ar purposes of this 1nveny tion, the coating a should approach the color i,

sensitivity of the eye, so far as average relative degree of chemical sensitiveness -to light of different wavelengths is concerned. A

commercial pan chromatic plate having sen.y sitive'ness in the yellow light near the sodiumv D lines, an infra-red limit at about the A lines, and low sensitiveness to wave lengths i shorter than the G lines, is satisfactory for intensities of the image will be uniform throughout the exposed surface of the plate. As explained in my said application illusive photography requires the impression upon the plate ofl certain diffusions, aberrations and distortions; in these respects the plate A alone satisfactorily recordsy the una e.

But for color photography, or for monochromatic photographic expression of panchromatic values improving the monochromatic picture, I prefer also todistribute the panchromatic sensitivity of the plate or other image receiving surface according to the similar distribution of sensitivity in the est seeing part of thel retina, the fovea centralis, is concentrated on aY surface about one degree of arc Wide, situated nearly centrally of the so called yellow spot, having an oval area about 6 degrees wide in. a hori zontal direction, and about 4: degrees wide in a vertical direction, and these areas of the retina are about centrally situated in a re` gion of sensitiveness substantially 40 degrecs, more or less wide (all as measured from the nodal point of the ocular lens), of less sensitivity than the yellow spot. The outside part of the last mentioned region is sensitive in lessened degrees to something beyond 40 degrees of the visual angle. These different regions of the eye vary substantiallyin respect to their power of excita-x tion by light of different colors. Thel result of a careful series of measurements in these particulars is plotted in Fig. 3. l In this figure the varioustraces show by their ordinates percentages 'of intensity of visual perception of the bright continuous spectrum from the cathode crater' of a car-y -bon arc light at respective regions of the retina, the wave-lengths being indicated 'according to an arbitrary scale by the abscissae. The following table of mean readings of these quantities by observation of a number of individual and normal eyes gives retina of the normal human eye. For clear f explanation it is necessary to understand. certainp'eculiarities of the eye with respectv Outside yellow spot.

Scale number,

Yellow spot.

Fovea centraljs.

c cabspawnsaeraasasessesssassesssassaresea assess-ae lt Will be observed that the maximum intensity at the fovea centralis is in the yellow light between Wave-lengths 7:5919p. and 7:599671.; that the equivalent maximum for the yellow spot is at 7:5850p. and that the visual intensity of the same light on the surrounding region 10 from the fovea is only about 85% of that for the fovea and yellow spot and maximum at about 7:5720n; but that this region exceeds the yellow spot and fovea in sensitivcncss to the greens and blues extending from 7:52707 to the ultra-violet visual limit.

If these values are determined in low illuminations, the normal eye undergoes not only pupillary expansion, but also changes its selective color sensitivity. The same spectrum when reduced in intensity to the photometric value at the D lines of l/132.5 of the illumination by a standard amyl lamp at a distance of one foot affects the retina according to the following table:

Mean reading reduced to. 100 maximum.

Scale number.

szssaaaeeaaaeaeaa saaaaasaaeaasaaaeaaw i Ul Ul The maximum perceptive intensity under these circumstances shifts into the green at about 7:52707, the perception of longer Wave-lengths .being markedly inhibited and of shorter Wave lengths markedly increased.

It Will now be apparent that an illusive photograph giving either a correct monochromatic translation of anchromatic values, or comprising a po ychromatic composite of monochrome elements, should faithfully record the different Values of the image perceived at the center of interest (by the fovea) at the region nearby (by the yellow spot) and at the outlying parts of the yislal angle (by the remainder of the retma Whatever the photographic means employed, a plate uniformly sensitive to color and uniformly exposed to the image in a camera can not compl with these conditions. This yinvention there ore comprises a genus of new devices enabling the plate to record variably in a chromatic sense the image at the center of interest and the image at diftering angles ofdeparture from the line of sight connoted by this center,

A preferred instance will now be described in connection with Figs. 1 and 2.

Let it be assumed that the photograph is to be made at an image plane corresponding to a known visual angle. This Will be true for any constant arrangement of lenses, such as the lens-system described and claimed in my said application. Different areas of a sensitive plate exposed in such an image plane will therefore correspond to the respective retinal surfaces of the eye. t

Provision is now made for maximum chromatic sensitiveness of the plate at a i maximum corresponding to the chromatic i region Y preferably an oval about six de-- maximumfof the fovea centralis in a region near the optical axis of the camera lens, for instance at f2, for decreased chromatic sensitiveness at the immediately surrounding region y2, and for further decreased sensitiveness to the maximum luminosity color and relatively increased sensitiveness to shorter wave lengths in a surrounding zone r2, and finally the remainder of the plate is rendered insensitive to all except the shorter pave-lengths for the remainder of its surace.

, These qualities may be imparted to the plate by suitable local treatment of the emulsion, but a preferred expedient is to influence the color of the image incident upon the plate with the aid of a suitable absorption screen D. This screen should be so devised as to impose no quantitative absorption, its function being to influence the color only of the light transmitted thereby without alteration of the uniformity of distribution in a quantitative sense of the light incident upon it. Figs. l and 2 illustra-te a preferred construction for this purpose. The screen isl in two parts, a colored plate d and a corrector plate D2, preferably of a colorless but variable transparency. v

As suggested above, the commercial panchrorhatic or orthochromatic plate is capable of sufcient accuracy of maximum color sensitiveness" at the right part of the spectrum, but in practice this is usuallyv attained with the aid of a color filter or absorption screen, which is generally arranged to exclude` some of thel light of shorter Wave length, in aid of the selective chemical treatvment of the film surface a, the absorption,i screen generally having the powers of transv-Y mission equivalent to a thin film ofvsodium bichromate or some other yellow dye or stain. The new screen d is of this nature at the region F, preferably a circular region subtending about one degree of arc with respect to the nodal point of the lens. The part of the plate f2 under this spot will then have a sensitiveness corresponding 'to the sensitiveness of the'fovea. l

The screen d is also provided with a grees long and about fourl degrees wide with respect to the nodal point. This region is colored with an attenuated dye or pigment ermitting more of the shorter Wave length ight to pass. The surrounding, prefera ly i circular regionvR ofthe absorption screen is colored with a still more attenuated dye. The remainder R of the absorption screen may be transparent and uncolored.

It will be observed that the selective ab- I sorption of the absorption screen d is distributed' as it is in the normal human eye,

- but if such a screen d were interposed alone between the plate and the lens, a substantial part of the quantity of light incident on the plate would be cut olf by the regions F, Y, R,

ofthe screen, whereas the illumination of lthe plate should be uniform so far as the absorption screen is condz, which may or may not be colored to in fluence the color of the light transmitted. For use with such plates as .those mentioned, preferably the corrector screen is colored with a neutral pigment. Its central region f corresponding to the spot F may be'quite transparent; the surrounding region y corresponding to the spot Y 'is lightly tinted; the larger circular region r corresponding to the region R is more heavily tinted, and the remainder of the surface r is still more deeply tinted.

The mutual arrangement of the screens d and d2 is such as to cause quantitative uniformity of transmission of light through them when they v are superposed. Such screens may be made of any suitable material and by any suitable process. They may be made of glass suitably pigmented; or they may b e made of clear glass having a suitable pigmented coating; or they may comprise clear glass enclosing films of gelatine or other transparent colloidal substance locally dyed or -pigmented as described.

Whatever the detail of the material yemployed the distribution of the pigment or coloring of the selective screen should substantially correspond in effect upon the transmitted light to the variable sensibility of the corresponding regions of the retina,

tween the central spot and the yellow spot region Y and the surrounding area R, and thediference between the region R and the regionR may be stillless in degree. The neutral corrector is correspondingly altered. In general, the photometric Idensity of the various regions of screens may vary among themselves inV proportion to the areas of the appropriate curves shown in Fig. 2.

It will be understood that the margins or y boundaries between the differently tinted areas of the componentsof the absorption screen should not be sharp or hard lines; these regions merge one. into the other with a gradual diffusion, the complemental parts of the plate being so merged or diffused in medina an opposite sense as to maintain uniformity orl photometric value of the superposed components throughout.

1. A photograph having a region depicted with maximum -eii'ect upon the photosensitive surface by one color of light and having other regions depicted with maximum eect upon the j photo-sensitive surfaces of another color of light, the picture gions depicting an image, said regions being subjected respectivelyy to diderent selective absor tions of color.

5. v hotograph depicting an image subject to the optical didusions, aberrations and distortions characteristic of normal human vision, and also havin@- depicted therein the eect of dierent co or-absorption of the image at dierent regions in respect to the axia center of interest.

6. A photography, having regions subjected respectively to dierent color absorptions of the image-forming iight at saidregions said image-formin light hein uniformfy aected by the a sorption'o light as regards the quantitative or photometric value of the light transmitted to the photosensitive surface.

.7. A photograph characterized by concentric regions subjected to diderent color absorption of the image-formin light, said regions having substantially tgne angular magnitude in respect to the nodal point of the image-forming lens system characteristic of regions of different color sensitivity in the retina of the normal human eye.

8. A photograph characterized by boncentric regions subjected to diHerent color absorption of the image-forming light, said regions having substantially the angular magnitude in respect to the nodal point of the image-forming lens system character'- istic of the fovea centralis, the yellow spot, and the central surrounding region of the normal human eye.

9. The art of photography comprising exposing a photo-sensitive surface to a polychromatic image subjected to selective chromatic absorption of light to degrees varying progressively from one region to another.

1.0. The art of photography comprising exposing a photo-sensitive surface to a polychromatic image subjected to selective chromatic absorption of light to degrees varying progressively from one region to another, and comprising as a step, subjecting the light of the image to compensating colorless obstruction.

1l. The art of photography comprising exposing a plate of uniform color sensi, tiveness toa polychromatic image subjected to selective chromatic absorption of light to degrees varying progressive y from'one region to another.

12. The art of photography comprising interposing between a hote-sensitive surface and an image-forming lens an absorption-screen having different powers of absorption in different regions, and a corrector screen having inversely arranged colorless absorption areas. v

13. The art of photography comprising exposing a photo-sensitive surface to a polychromatic image subjected to uniform absorption of its light,'the color of the absorbed light varying from region to region of the image.

Signed by me at Boston, Massachusetts, this thirtiethv day of December, 1919.

ADELBERT s, JR. 

